/*
 * x86_emulate.h
 *
 * Generic x86 (32-bit and 64-bit) instruction decoder and emulator.
 *
 * Copyright (c) 2005 Keir Fraser
 *
 * From: xen-unstable 10676:af9809f51f81a3c43f276f00c81a52ef558afda4
 *
 * Copyright (c) 2011 Joyent, Inc.
 */

#ifndef _ASM_X86_KVM_X86_EMULATE_H
#define	_ASM_X86_KVM_X86_EMULATE_H

#include <sys/stdint.h>

struct kvm_vcpu;
struct x86_emulate_ctxt;
#ifdef _KERNEL
/*
 * x86_emulate_ops:
 *
 * These operations represent the instruction emulator's interface to memory.
 * There are two categories of operation: those that act on ordinary memory
 * regions (*_std), and those that act on memory regions known to require
 * special treatment or emulation (*_emulated).
 *
 * The emulator assumes that an instruction accesses only one 'emulated memory'
 * location, that this location is the given linear faulting address (cr2), and
 * that this is one of the instruction's data operands. Instruction fetches and
 * stack operations are assumed never to access emulated memory. The emulator
 * automatically deduces which operand of a string-move operation is accessing
 * emulated memory, and assumes that the other operand accesses normal memory.
 *
 * NOTES:
 *  1. The emulator isn't very smart about emulated vs. standard memory.
 *     'Emulated memory' access addresses should be checked for sanity.
 *     'Normal memory' accesses may fault, and the caller must arrange to
 *     detect and handle reentrancy into the emulator via recursive faults.
 *     Accesses may be unaligned and may cross page boundaries.
 *  2. If the access fails (cannot emulate, or a standard access faults) then
 *     it is up to the memop to propagate the fault to the guest VM via
 *     some out-of-band mechanism, unknown to the emulator. The memop signals
 *     failure by returning X86EMUL_PROPAGATE_FAULT to the emulator, which will
 *     then immediately bail.
 *  3. Valid access sizes are 1, 2, 4 and 8 bytes. On x86/32 systems only
 *     cmpxchg8b_emulated need support 8-byte accesses.
 *  4. The emulator cannot handle 64-bit mode emulation on an x86/32 system.
 */
/* Access completed successfully: continue emulation as normal. */
#define	X86EMUL_CONTINUE	0
/* Access is unhandleable: bail from emulation and return error to caller. */
#define	X86EMUL_UNHANDLEABLE	1
/* Terminate emulation but return success to the caller. */
/*
 * X86EMUL_PROPAGATE_FAULT: propagate a generated fault to guest
 * X86EMUL_RETRY_INSTR:	retry the instruction for some reason
 * X86EMUL_CMPXCHG_FAILD: cmpxchg did not see expected value
 */
#define	X86EMUL_PROPAGATE_FAULT	2
#define	X86EMUL_RETRY_INSTR	2
#define	X86EMUL_CMPXCHG_FAILED	2

typedef struct x86_emulate_ops {
	/*
	 * read_std: Read bytes of standard (non-emulated/special) memory. Used
	 * for descriptor reading.
	 *
	 *  @addr:  [IN ] Linear address from which to read.
	 *  @val:   [OUT] Value read from memory, zero-extended to 'u_long'.
	 *  @bytes: [IN ] Number of bytes to read from memory.
	 */
	int (*read_std)(unsigned long, void *,
	    unsigned int, struct kvm_vcpu *, uint32_t *);

	/*
	 * fetch: Read bytes of standard (non-emulated/special) memory. Used for
	 * instruction fetch.
	 *
	 *  @addr:  [IN ] Linear address from which to read.
	 *  @val:   [OUT] Value read from memory, zero-extended to 'u_long'.
	 *  @bytes: [IN ] Number of bytes to read from memory.
	 */
	int (*fetch)(unsigned long, void *,
	    unsigned int, struct kvm_vcpu *, uint32_t *);

	/*
	 * read_emulated: Read bytes from emulated/special memory area.
	 *
	 *  @addr:  [IN ] Linear address from which to read.
	 *  @val:   [OUT] Value read from memory, zero-extended to 'u_long'.
	 *  @bytes: [IN ] Number of bytes to read from memory.
	 */
	int (*read_emulated)(unsigned long, void *, unsigned int,
	    struct kvm_vcpu *);

	/*
	 * write_emulated: Write bytes to emulated/special memory area.
	 *
	 *  @addr:  [IN ] Linear address to which to write.
	 *  @val:   [IN ] Value to write to memory (low-order bytes used as
	 *		  required).
	 *  @bytes: [IN ] Number of bytes to write to memory.
	 */
	int (*write_emulated)(unsigned long, const void *, unsigned int,
	    struct kvm_vcpu *);

	/*
	 * cmpxchg_emulated: Emulate an atomic (LOCKed) CMPXCHG operation on an
	 * emulated/special memory area.
	 *
	 *  @addr:  [IN ] Linear address to access.
	 *  @old:   [IN ] Value expected to be current at @addr.
	 *  @new:   [IN ] Value to write to @addr.
	 *  @bytes: [IN ] Number of bytes to access using CMPXCHG.
	 */
	int (*cmpxchg_emulated)(unsigned long, const void *, const void *,
	    unsigned int, struct kvm_vcpu *);

} x86_emulate_ops_t;
#endif /* _KERNEL */

/* Type, address-of, and value of an instruction's operand. */
typedef struct operand {
	enum { OP_REG, OP_MEM, OP_IMM, OP_NONE } type;
	unsigned int bytes;
	unsigned long val, orig_val, *ptr;
} operand_t;

typedef struct fetch_cache {
	uint8_t data[15];
	unsigned long start;
	unsigned long end;
} fetch_cache_t;

typedef struct decode_cache {
	uint8_t twobyte;
	uint8_t b;
	uint8_t lock_prefix;
	uint8_t rep_prefix;
	uint8_t op_bytes;
	uint8_t ad_bytes;
	uint8_t rex_prefix;
	struct operand src;
	struct operand src2;
	struct operand dst;
	int has_seg_override;
	uint8_t seg_override;
	unsigned int d;
	unsigned long regs[NR_VCPU_REGS];
	unsigned long eip, eip_orig;
	/* modrm */
	uint8_t modrm;
	uint8_t modrm_mod;
	uint8_t modrm_reg;
	uint8_t modrm_rm;
	uint8_t use_modrm_ea;
	int rip_relative;
	unsigned long modrm_ea;
	void *modrm_ptr;
	unsigned long modrm_val;
	struct fetch_cache fetch;
} decode_cache_t;

#define	X86_SHADOW_INT_MOV_SS	1
#define	X86_SHADOW_INT_STI	2

typedef struct x86_emulate_ctxt {
	/* Register state before/after emulation. */
	struct kvm_vcpu *vcpu;

	unsigned long eflags;
	/* Emulated execution mode, represented by an X86EMUL_MODE value. */
	int mode;
	uint32_t cs_base;

	/* interruptibility state, as a result of execution of STI or MOV SS */
	int interruptibility;

	/* decode cache */
	struct decode_cache decode;
} x86_emulate_ctxt_t;

/* Repeat String Operation Prefix */
#define	REPE_PREFIX	1
#define	REPNE_PREFIX	2

/* Execution mode, passed to the emulator. */
#define	X86EMUL_MODE_REAL	0	/* Real mode. */
#define	X86EMUL_MODE_VM86	1	/* Virtual 8086 mode. */
#define	X86EMUL_MODE_PROT16	2	/* 16-bit protected mode. */
#define	X86EMUL_MODE_PROT32	4	/* 32-bit protected mode. */
#define	X86EMUL_MODE_PROT64	8	/* 64-bit (long) mode. */

/* Host execution mode. */
#define	X86EMUL_MODE_HOST X86EMUL_MODE_PROT64

#ifdef _KERNEL
extern int x86_decode_insn(struct x86_emulate_ctxt *,
    struct x86_emulate_ops *);
extern int x86_emulate_insn(struct x86_emulate_ctxt *,
    struct x86_emulate_ops *);
#endif /* _KERNEL */
#endif /* _ASM_X86_KVM_X86_EMULATE_H */
